Question

find the area of triangle if sides are 42 cm ,39 cm,45 cm

Answer 1

Hi ,

Let a = 42cm , b = 39 cm , c = 45cm

are three sides of a Triangle.

s = ( a + b + c ) /2

= ( 42 + 39 + 45 ) /2

= 126/2

= 63

s - a = 63 - 42 = 21

s - b = 63 - 39 = 24

s - c = 63 - 45 = 18

Therefore ,

By Heron's formula ,

Area of the triangle ,

∆ = √ s( s - a ) ( s - b ) ( s - c )

= √ 63 × 21 × 24 × 18

= √ 9 × 7 × 7 × 3 × 2 × 2 × 6 × 6 × 3

= √ ( 3×3×3×3)×(7×7)×(6×6)×(2×2)

= 3 × 3 × 7 × 6 × 2

= 756 cm²

I hope this helps you.

:)